Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEADgrafted

Changes:

Make expedited grace periods expedite normal RCU callbacks

Miscellaneous fixes:
 * Improve diagnostic output with character task states.
 * Mark accesses to inform KCSAN of concurrency design.
 * Move from kmalloc() to kmalloc_obj().
 * Documentation updates.
 * Improve handling of RCU deferred quiescent states.
 * Clean up unused function arguments and structure fields.
 * Reduce show_rcu_gp_kthreads() stack space.

Tasks RCU updates:
 * Clean up after SRCU re-implementation of Tasks Trace RCU.
 * Mark accesses to inform KCSAN of concurrency design.
 * Add ->lazy_timer status to diagnostic output.
 * Remove an unnecessary memory barrier.
 * Fix a data race, courtesy of KCSAN.
 * Documentation updates.
 * Convert cond_resched_tasks_rcu_qs() from macro to static inline
   function.

SRCU updates:
 * Add Rust helpers for SRCU.
 * Avoid losing queued work at cleanup_srcu_struct() time.

Torture-test updates:
 * Preparation work for immediate RCU priority deboosting.
 * Test RCU readers from real interrupt handlers (as opposed to softirq).
 * Simplify code through use of cpumask_next_wrap().
 * Improve diagnostic output with character task states.
 * Add rcutorture.nwriters parameter to allow lightweight stall testing,
   and rcutorture.stall_only to make doing so easier.
 * Test an RCU Tasks Trace grace period implying an RCU grace period.
 * Make RCU Tasks Trace torturing track reader batches.
 * Fix a data race, courtesy of KCSAN.
 * Plug a shuffle_tmp_mask memory leak on kthread spawn failure.

1 files changed, 173 insertions, 0 deletions

diff --git a/drivers/misc/ibmasm/command.c b/drivers/misc/ibmasm/command.c
new file mode 100644
index 000000000..6b037675f
--- /dev/null
+++ b/drivers/misc/ibmasm/command.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/*
+ * IBM ASM Service Processor Device Driver
+ *
+ * Copyright (C) IBM Corporation, 2004
+ *
+ * Author: Max Asböck <amax@us.ibm.com>
+ */
+
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include "ibmasm.h"
+#include "lowlevel.h"
+
+static void exec_next_command(struct service_processor *sp);
+
+static atomic_t command_count = ATOMIC_INIT(0);
+
+struct command *ibmasm_new_command(struct service_processor *sp, size_t buffer_size)
+{
+	struct command *cmd;
+
+	if (buffer_size > IBMASM_CMD_MAX_BUFFER_SIZE)
+		return NULL;
+
+	cmd = kzalloc_obj(struct command);
+	if (cmd == NULL)
+		return NULL;
+
+
+	cmd->buffer = kzalloc(buffer_size, GFP_KERNEL);
+	if (cmd->buffer == NULL) {
+		kfree(cmd);
+		return NULL;
+	}
+	cmd->buffer_size = buffer_size;
+
+	kref_init(&cmd->kref);
+	cmd->lock = &sp->lock;
+
+	cmd->status = IBMASM_CMD_PENDING;
+	init_waitqueue_head(&cmd->wait);
+	INIT_LIST_HEAD(&cmd->queue_node);
+
+	atomic_inc(&command_count);
+	dbg("command count: %d\n", atomic_read(&command_count));
+
+	return cmd;
+}
+
+void ibmasm_free_command(struct kref *kref)
+{
+	struct command *cmd = to_command(kref);
+
+	list_del(&cmd->queue_node);
+	atomic_dec(&command_count);
+	dbg("command count: %d\n", atomic_read(&command_count));
+	kfree(cmd->buffer);
+	kfree(cmd);
+}
+
+static void enqueue_command(struct service_processor *sp, struct command *cmd)
+{
+	list_add_tail(&cmd->queue_node, &sp->command_queue);
+}
+
+static struct command *dequeue_command(struct service_processor *sp)
+{
+	struct command *cmd;
+	struct list_head *next;
+
+	if (list_empty(&sp->command_queue))
+		return NULL;
+
+	next = sp->command_queue.next;
+	list_del_init(next);
+	cmd = list_entry(next, struct command, queue_node);
+
+	return cmd;
+}
+
+static inline void do_exec_command(struct service_processor *sp)
+{
+	char tsbuf[32];
+
+	dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));
+
+	if (ibmasm_send_i2o_message(sp)) {
+		sp->current_command->status = IBMASM_CMD_FAILED;
+		wake_up(&sp->current_command->wait);
+		command_put(sp->current_command);
+		exec_next_command(sp);
+	}
+}
+
+/*
+ * exec_command
+ * send a command to a service processor
+ * Commands are executed sequentially. One command (sp->current_command)
+ * is sent to the service processor. Once the interrupt handler gets a
+ * message of type command_response, the message is copied into
+ * the current commands buffer,
+ */
+void ibmasm_exec_command(struct service_processor *sp, struct command *cmd)
+{
+	unsigned long flags;
+	char tsbuf[32];
+
+	dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));
+
+	spin_lock_irqsave(&sp->lock, flags);
+
+	if (!sp->current_command) {
+		sp->current_command = cmd;
+		command_get(sp->current_command);
+		spin_unlock_irqrestore(&sp->lock, flags);
+		do_exec_command(sp);
+	} else {
+		enqueue_command(sp, cmd);
+		spin_unlock_irqrestore(&sp->lock, flags);
+	}
+}
+
+static void exec_next_command(struct service_processor *sp)
+{
+	unsigned long flags;
+	char tsbuf[32];
+
+	dbg("%s:%d at %s\n", __func__, __LINE__, get_timestamp(tsbuf));
+
+	spin_lock_irqsave(&sp->lock, flags);
+	sp->current_command = dequeue_command(sp);
+	if (sp->current_command) {
+		command_get(sp->current_command);
+		spin_unlock_irqrestore(&sp->lock, flags);
+		do_exec_command(sp);
+	} else {
+		spin_unlock_irqrestore(&sp->lock, flags);
+	}
+}
+
+/*
+ * Sleep until a command has failed or a response has been received
+ * and the command status been updated by the interrupt handler.
+ * (see receive_response).
+ */
+void ibmasm_wait_for_response(struct command *cmd, int timeout)
+{
+	wait_event_interruptible_timeout(cmd->wait,
+				cmd->status == IBMASM_CMD_COMPLETE ||
+				cmd->status == IBMASM_CMD_FAILED,
+				timeout * HZ);
+}
+
+/*
+ * receive_command_response
+ * called by the interrupt handler when a dot command of type command_response
+ * was received.
+ */
+void ibmasm_receive_command_response(struct service_processor *sp, void *response, size_t size)
+{
+	struct command *cmd = sp->current_command;
+
+	if (!sp->current_command)
+		return;
+
+	memcpy_fromio(cmd->buffer, response, min(size, cmd->buffer_size));
+	cmd->status = IBMASM_CMD_COMPLETE;
+	wake_up(&sp->current_command->wait);
+	command_put(sp->current_command);
+	exec_next_command(sp);
+}